Personal computers (PCs) may be provided with one of a number of types of microprocessor integrated circuits (e.g., Intel.RTM. 486, Pentium.RTM. or the like, Motorola.RTM. 68000 series, PowerPC.RTM. or other type of processor). For the purposes of this application, the term "PC" shall be construed to include desktop personal computers, work stations, lap top, portable, notebook, palm top or other types of computer systems.
For manufacturers of PCs, particularly in the IBM.RTM. compatible or ISA type environment, it may be desirable from a marketing standpoint to offer PCs with a range of processor types and/or speeds in a corresponding array of price ranges. Thus, for example, a line of PCs may be offered with different processors, from 486 type processors (typical of lower priced PCs at the time of filing of the present application) to Pentium.RTM. processors (usually offered in higher priced PCs at the time of filing of the present application).
In order to reduce manufacturing and inventory costs, it may be desirable to provide a common PC design which may accept either 486 or Pentium.RTM. processors. The use of the 486 and Pentium.RTM. processors is offered by way of example only, and the present invention is not limited to use of such processors. Other grades or ranges of processors may be applied within the spirit and scope of the present invention. However, such disparate processor types may require different clock speeds, data widths or the like, and thus it may be difficult to provide a single PC design which may accept disparate processor types.
In addition, it may be desirable to offer a PC design which may be upgraded from a lower power processor (e.g., 486 type) to a higher power processor (e.g., Pentium.RTM. type). Again, however, such upgradeability may present challenges due to the different processing requirements of the different processors, including clock speeds and data width.
In portable computers operating on battery power or in other energy saving computer systems, it may be desirable to reduce power consumption to prolong battery life or for thermal management considerations. In such systems, it may be desirable to shut down components not in use in order to conserve energy. However, some components, when shut down, may induce delays in processing when reactivated, causing delay or system failure. For example, a system memory cache, when shut down, may induce delays when restarted, negating its purpose of speeding processing or in a worse case, causing system failure.